Furnace door



Oct. 21, 1941. HR. LOXTERMAN FURNACE DOOR Filed March 30, 1940 2 Sheets-Sheet l figl.

- I I NVENTOR Henry Russell Loxferman 4 1 Oct. 21, 1941. I LQXTERMAN 2,259,900

FURNACE DOOR Filed March 30, 1940 2 Sheets-Shet 2 I\ 17 FT I KL F r E I ILLLLL Lilli L l-L LITIIIII III 11 L151 I II I LUTFI'TFTTIIIIIIII I I I 'l I I I I INVENTOR Henry Russell loxfermarl 5 5 4 1 1 M "v Z 6 y M Patented Oct. 21, 1941 warren srares PATENT, OFFICE.

FURNACE DOOR Henry Russell Loxterman, Aspinwall, Pa., as-

signor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application March '30, 1940, Serial No. 327,000

4 Claims.

The present invention relates to furnaces and, more particularly, to the doors utilized for covering the furnace charging or discharging openings.

In the operation of various types of heating or melting furnaces in which the material is charged to the furnace or removed therefrom through openings in a side wall of the furnace which are normally closed by doors, it is some times desirable to provide two or more doors which may be operated together or independently. The purpose of providing two or more doors over the furnace opening is to permit a variation in the size of the opening of the furnace to suit the particular charge which is being placed into or removed from the furnace. The provision of two or more doors over a single furnace opening without any door jamb between adjacent doors is particularly desirable where a large opening is occasionally required for unusual or emergency conditions, and Where a smaller opening will suffice for ordinary operations. By using two or more doors under such circumstances a material amount of heat can be conserved. If only a single large door is provided under such circumstances a substantial amount of heat is lost from the furnace each time it is necessary to open the furnace. A particular instance in which a very substantial amount of heat can be conserved is in the case of heating furnaces for heating slabs preparatory to rolling. In furnaces of this type a large opening or door must be provided for emergency purposes although a furnace opening considerably smaller than that required for emergency purposes is required for ordinary operations. Occasionally during the rolling of slabs it is necessary to reheat the material due to a breakdown in the rolling equipment before the rolling of the slab has been completed. Under such circumstances a furnace opening considerably larger than that required to take care of the article before rolling is necessary to permit the partially rolled slabs to be placed in the furnace and reheated. Many other instances could be cited in which it is desirable to provide a plurality of doors over the same furnace opening without jambs between adjacent doors, but this illustration will suflice for present purposes.

Prior to the making of the present invention it was the usual practice, in installations of the character to which the present invention relates, to hang two or more ordinary water cooled furnace doors side by side adjacent a single water cooled door frame surrounding the furnace opening, each door resting against one leg and the formed between the adjacent door ends.

lintel of the frame and abutting the adjacent door at the center. Because of manufacturing limitations and warpage and distortion in usage, substantial openings or cracks are present or are Furnaces of this character are usually'operated at pressures somewhat above atmospheric pressure and, consequently,- in installations of this type serious leakage of hot gases occurs between the adjacent ends of the doors. In addition, due to the positive pressure prevailing in such furnaces, the flames normally lick out between the adjacent door ends. These flames and the leakage of hot gases result in a concentration of relatively high temperatures at the door ends and elsewhere along the inner faces of the doors, and this materially reduces the life of the doors. In

normal operation of furnaces of this character the furnace pressures are not uniform within the furnace and frequently near the hearth of the furnace pressures somewhat below atmospheric pressure will prevail, whereas,- adjacent the roof of the furnace pressures above atmospheric pressure will prevail. Under such operating conditions cold air is drawn into the furnace through the cracks near the bottom of the door and cools the furnace, and hot furnace gases are discharged through the cracks near the tops of the doors, resulting in a material lowering of the eificiency of the furnace.

Prior to the making of the present invention several attempts have been made to provide special joints between such doors. In one such attempt it was proposed to employ a separate sealing member bridging the joint between adjacent doors. Such a sealing member is objectionable as it increases the cost of construction and operation of the furnace, due to' the fact that provision must be made for raising and lowering the special sealing member along with the doors when both of them are raised vertically along the door frame, and appropriate provision made to either retain the special sealing member in position when only one door is opened or to move it vertically along with the particular door which is to be opened.

In accordance with. the present invention, I overcome the difficulties which have been encountered heretofore in installations of the character mentioned above without the necessity of providing an auxiliary sealing member. In accordance with my invention, I provide a beveled lap fit between adjacent doors, the doors abutting each other in such a manner as to provide a positive seal. By providing substantial parallel engaging surfaces on adjacent ends of the doors extending obliquely relatively to the plane of the doors, the doors can be seated against each other so as to effectively seal the furnace opening against any leakage between the doors. The beveled construction of the adjacent door ends permits doors made to practical manufacturing tolerances to mate at 'the center when hung against the frame. In accordance with the present invention I also provide for water cooling of the overlapping end sections of adjacent doors so as to minimize or eliminate distortion of the" abutting surfaces of the doors by the high furnace temperatures. As will be pointed out more fully hereinafter, the overlapping joint construction which I provide also affords a maximum lap contact surface with a minimum of water cooling exposed to the furnace. By virtue of this C011:- struction the furnace door is protected with the least lossof heat from the furnace.

The lap construction which I provide for the abutting ends of the furnace doors for effecting the sealing is of such character that the furnace doors can be slid vertically relative to each other without encountering any difliculties and without detrimentally affecting the seal between the doors. It is also of such character that some relative movement of the doors out of the normal plane thereof can be permitted without disturbing the seal provided by this construction.

In the accompanying drawings I have illustrated the present invention as applied to a furnace embodying two water cooled panel type doors cooperating with a single furnace door frame to close the furnace opening. It will be apparent, however, that the present invention may be applied to furnaces in which it is desirable to utilize more than two furnace doors cooperating with a single door frame surrounding the furnace opening.

In the accompanying drawings- Figure l is a front elevational view of a furnace embodying two doors cooperating with a single door frame;

Figure 2 is a partial section taken along the line IIII of Figure 1;

Figure 3 is a partial horizontal section along the line III-III of Figure 1;

Figure 4 is a front elevational view of one of the doors shown in Figure 1;

Figure 5 is a vertical section along the line VV of Figure 4; and

Figure 6 is a partial sectional view showing the character of the joint formed by the doors constructed in accordance with my invention.

In the embodiment shown in the drawings, the opening 2 of the furnace 3 is closed by the vertically movable doors 4 and 5. The outer edge of the door 4 bears against the leg 6 of the water cooled door frame 1, and the outer end of the door 5 cooperates with and 'bears against the vertically extending leg 8 of the water cooled door frame. The upper end of each door normally bears against the lintel 9 of the door frame I and, as the doors are moved vertically in order to provide access to the furnace, they slide upwardly along the legs and the lintel portion of the water cooled frame.

As the water cooled frame per se forms no part of the present invention it will not be specifically described herein. It will be sufiicient to state that it is formed of suitable size and configurafurnace opening, and is positioned against the door.

door jamb indicated generally by the reference character II). It is provided with appropriate water inlets H and outlets l2 in order to provide for circulation of water through the entire frame including the nose portion l3, which extends inwardly beneath the top of the furnace opening.

The two doors 4 and 5 are of identical construction and, consequently, only one will be specifically described. It is desirable to have the two doors of identical construction so that either may be used over the right or left half of the furnace opening. If it is not deemed necessary -to make the doors interchangeable it is not necessary to have them of identical construction. However, in most installations this interchangeability is highly desirable and need not be sacrificed by virtue of the character of the seal provided for the space between the two doors.

The door 4 is of the panel type wherein the brickwork M or refractory material is built and bonded into vertical openings in the frame. The frame proper is formed of a plurality of metallic plates l5 suitably secured together by welding so as to provide a support for the brickwork l4 and passageways I6 through which water may be circulated to prevent overheating of the door. An inlet I! is provided at the top of the frame for supplying water thereto through appropriate piping I8 positioned within the frame. An outlet !9 is also provided in the top of the frame for permitting the discharge of the water which is circulated through the door. 7

As stated above, in accordance with my invention I provide for an overlap between adjacent ends of the doors. One end of each door is provided with a surface 20 which extends at right angles to the inner face of the door. This end is also provided with a plane surface 2| which extends at right angles to the outer face of the These two plane surfaces 20 and 2| are joined together by a plane surface 22 which extends obliquely with reference to these plane surfaces 20 and 2| and with respect to the general plane of the door. The other end of each door is provided with similar plane surfaces 23, 24 and 25, These plane surfaces are parallel to the surfaces 20, 2| and 22 and they cooperate with each other in order to form the lap joint between adjacent ends of the doors 4 and 5. The plane surfaces just described, which are on the outer ends of the doors when they are positioned as shown in Figures 1 and 3, serve no new function whatever but, as stated above, by making the two doors exactly alike it is possible to interchange them whenever desirable.

When the doors are in position over the furnace opening the outer edges bear against the legs of the door frame and the upper edges thereof bear against the lintel of the frame. The inner ends of the doors bear against each other tically throughout substantially the entire height of the door, will bear against the plane surface 22 which also extends substantially throughout the entire plane of the furnace, and a very effective seal against egress of products of combustion will be formed. The surfaces 20 and 23 and aesaeoo' the surfaces 2i and 24 need not be intimately engaged witheach other when the doors are in position in order to seal the opening, as the obliquely extending surfaces 22 and 25 will provide the necessary sealing of the furnace.

It will be evident from what has been stated above that even though the doors are not accurately positioned an effective seal will be provided because the obliquely extending sealing surfaces 22 and 25 will remain in contact with each other even though the one door is not in exactly the same plane as the other.

The doors hang in front of the furnace opening on cables 26 or on some other suitable suspension means, The cables 26 are attached to lugs 21 which are formed on the top of each door. Any suitable apparatus may be provided for raising or lowering the doors by means of these cables.

The door frame may have a slight batter or taper so that the door will raise and lower on an incline instead of vertically, whereby the weight of the door holds it against the frame to make a seal at the leg and lintel portions of the frame. Also, if desired, the suspending cables may be slightly inclined in a plane parallel to the face of the frame so as to cause the doors to bear against one another at the lap joint between them, thereby insuring that the doors will not spread apart and make an objectionable gap at this point.

The edges of the doors coming in contact with the water cooled frame are water cooled. As a consequence, the form and alinement of the edges of the doors are maintained substantially true and free from any temperature distortion. Water cooling for such a purpose is quite old and, of course, is preferred for furnace doors regardless of the character of the seal to increase the life of the brickwork and of the door generally, and to improve the comfort of the furnace operator. In addition, the ends of the doors cooperating with each other to form the seal between the doors are water cooled, Where the beveled lap joint of the present invention is utilized the flow of the cooling water is rendered more effective than where no such beveled arrangement is provided. The obliquely extending surfaces provide a substantial opening for water to flow between the inside and outside portions of the vertical edges of the doors. If the surface 22, for example, were parallel to the face of the door and the other dimensions were as substantially shown in the drawings, the end of the door frame would be divided into two rectangular water compartments, one next to the furnace and the other outside of the furnace. The other next to the furnace would have to accomplish practically all of the cooling and the compartment adjacent the outer face of the door would have a much less cooling burden to bear. Unless the lap portion 22 were very narrow or the water cooling directly exposed to temperatures greatly increased, these two compartments would have no communication between each other and the water in the outer portion would not have an opportunity to mingle with that in the inner portion to reduce the temperature and render the cooling effective. It will thus be seen that the lap joint construction which I provide affords a substantial lap contact surface between adjacent door ends with a minimum of water cooling exposed to the furnace. This is highly desirable in a furnace door construction as it renders the cooling water available at lower temperatures where the cooling is most needed.

It will be evident from what has been stated above that my invention is not limited to doors of the particular type shown in the drawings. It has been illustrated in connection with panel doors of the type disclosed in United States Reissue Letters Patent No. 17,864, wherein the brickwork is built and bonded into vertical openings in the water cooled frame, but my invention may readily be applied to doors such as those shown in United States Letters Patent 1,690,619, or to any other desired construction.

It will also be evident from what has been stated above that my invention is not limited to structures embodying two doors. My invention may be applied wherever two or more doors are utilized for covering a single opening. Where three doors are used the cables on the center door are preferably Vertical and those on the outer doors are preferably at a slight angle to the vertical so as to cause the oblique plane surfaces of adjacent ends of adjacent doors to bear against each other tightly, in order to seal the furnace opening. It is not necessary that the cables be positioned at an angle to the vertical where the present invention is utilized as entirely satisfactory results are obtained where the cables are positioned vertically, if sufficient care is utilized in locating the sheaves to cause the oblique plane surfaces to abut each other.

While I have shown and described a preferred embodiment of my invention, it will be understood that various different arrangements of the abutting ends of the doors may be provided within the scope of the present invention. My invention may be embodied otherwise than as shown in the drawings within the scope of the appended claims.

I claim:

1. In a furnace having a door opening of a length substantially equal to the width of two or more doors, the combination of a furnace door frame extending around said door opening, and a plurality of doors for closing said opening positioned in end abutting relationship across the opening and movable individually vertically along said frame, adjacent ends of adjacent doors having parallel surfaces in slidable engagement with each other extending obliquely to the plane of said doors.

2. In a furnace having a door opening of a length substantially equal to the width of two or more doors, the combination of a furnace door frame extending around said door opening, a plurality of doors for closing said opening positioned in end abutting relationship across the opening and movable individually vertically along said frame, adjacent ends of adjacent doors having parallel surfaces in slidable engagement with each other extending obliquely to the plane of said doors, and each of said ends having at least one other plane surface extending at an angle to said oblique surfaces.

3. In a furnace having a door opening of a length substantially equal to the width of two or more doors, the combination of a furnace door frame extending around said door opening, a plurality of doors for closing said opening positioned in end-abutting relationship across the opening and movable individually vertically along said frame, adjacent ends of adjacent doors having parallel surfaces in slidable engagement with each other extending obliquely to the plane of said doors, and means for supporting at least one of whereby an eifective seal is obtained and maintained between the doors in any adjusted position.

. 4. In a furnace having a door opening of a length substantially equal to the width of two or more doors, a plurality of doors for closing said opening positioned in end abutting relationship the doors so that it is biased toward the other, across the opening and movable individually ver-' tically along the opening, adjacent ends of adjacent doors having water cooling passageways therein the adjacent walls of which have parallel v engaging surfaces extending obliquely relative to the plane of said doors, and means for passing a cooling fluid through each of said passageways. HENRY RUSSELL LO-X'IERMAN. 

